1. Field of the Invention
This invention relates to accelerometers in which the acceleration value is deduced from that of the forces required to hold a test weight in or bring it back to a position defined with respect to the body of the apparatus. It concerns more particularly accelerometers in which these forces are electrostatic in nature.
An accelerometer of this type is known in Published French patent application No. FR-A-2511509 of Dec. 31, 1980 in which the test weight is cruciform in shape and is formed of three planar rectangular plates wherein the planes are orthogonally arranged two by two.
2. Description of the Prior Art
Described in U.S. Pat. application Ser. No. 584,405 filed Feb. 28, 1984 is a test weight comprising members of planar surfaces, oppositely arranged in parallel two by two, thereby forming three pairs of surface members, where the directions normal to these members correspond to the sensitive axes of the triaxial accelerometer. In the patent application, the typical shape envisioned for the test weight is a cube.
This invention deals essentially with the shape of the test weight and the definition of the suspension electrode systems for an inertial navigation electrostatic accelerometer in which the test weight must carry a high surface to weight ratio.
An object of this invention is to simplify the design of the accelerometer through a reduction in the number of components used therein and a simplification of the shapes thereof.
A further object hereof is to improve rigidity of the test weight without increasing the weight while retaining a sizeable surface area and thereby secure better decoupling between the natural vibration modes of the test weight and those of the electrostatic suspension.
A further object hereof is to utilize systems of deposited planar electrodes (which besides simplifying the design, permits accurate electrode positioning with respect to the test weight).
A further object hereof is to curtail the thermal sensitivity of the accelerometer through the use of suitable shims for electrode positioning.